Issue encoding, decoding and downloading blob (base64) data from MySQL database

First post... please be nice....

I am trying to upload and download files to a MySQL database but the files are being returned corrupt and I'm not sure why. I am using homestead as my local development environment. Would this not be an issue once pushed to an actual server? The details of the data transactions are detailed below:

I am using Dropzone.js to upload files to the server. When they arrive I encode them in binary using php's base64_decode() and store them in a BLOB data column in the table:

/**
     * Upload contact documents
     */
    public function postUpload()
    {
        $contact_id = $this->request->header('X-CONTACT-ID');
        $count = count($_FILES['file']['name']);

        // check that the file don't exceed the 20MB max gile size
        for($i = 0; $i < $count; $i++)
        {        
            if($_FILES['file']['size'][$i] > 20480000) // 20MB
            {
                return $this->respondBadRequest(['One or more of the files exceed the 20MB maximum file size.']);
            }
        }

        for($i = 0; $i < $count; $i++)
        {
            $document = new $this->document;
            $document->belongs_to = $contact_id; // contact_id
            $document->file_name = $_FILES['file']['name'][$i];
            $document->mime_type = $_FILES['file']['type'][$i];
            $document->size = $_FILES['file']['size'][$i];
            $document->data = base64_encode(file_get_contents($_FILES['file']['tmp_name'][$i]));;
            $document->uploaded_by = $this->auth->user()->id;
            $document->save();
        }
    
        return $this->respondHttpCreated();
    }

Then when I download them the files, I decode using php's base64_decode(), set headers and return the file contents:

/**
     * Get file
     */
    public function getShow($id)
    {
        $document = $this->document->find($id);

        if(!$id)
            $this->respondNotFound();

        $file_contents = base64_decode($document->data);

        return response($file_contents)
            ->header('Cache-Control', 'no-cache private')
            ->header('Content-Description', 'File Transfer')
            ->header('Content-Type', $document->mime_type)
            ->header('Content-length', strlen($file_contents))
            ->header('Content-Disposition', 'attachment; filename=' . $document->file_name)
            ->header('Content-Transfer-Encoding', 'binary');

    }

Any idea what I'm doing wrong?